1. Field of the Invention
The present invention relates to sleeping compartments for vehicles, and more particularly to a stowable step ladder for such compartments which may be compacted for stowage.
2. Description of the Problem
Fold down overhead beds and bunkbeds are a common response to the desire to provide sleeping accommodations in a compartment with limited space, such as found on railroad passenger trains and in long haul trucks. Ease of access to the upper berth or berths of a bunkbed, or to a fold down overhead bed, requires a ladder of some sort. Due to constraints of space, access to the berths is typically limited to one side of the berth and, for the convenience of the passenger, the ladder is preferably located along the same side of the bed, although in some cases steps and hand grips are built into cabinets located at one end of the berth. For the convenience of the lower berth occupant, and to save space, where ladders are used, they are preferably stowable. Making the ladder stowable is aided by making the ladder foldable or collapsible.
Volvo in its VN 770 series trucks provides a stowable ladder based on a parallelogram mechanism. The design stows cleanly and tightly, but uses gravity to aid opening. This means that the device can open for a tired user more quickly than expected or can fall open if a passenger loses his grip while the vehicle is moving. What is desired is a stowable ladder which can be opened with one hand, but which does not make use of gravity to unfold.
According to the invention there is provided a stowable ladder mechanism for an overhead bed or an upper berth of a bunk bed. The ladder rests on a horizontal support surface. A horizontal linear guide is vertically spaced above the horizontal support surface and associated with a bed or berth. The rungs of the ladder are supported between two vertical uprights, one of which is fixed at one end of the berth and the second of which is coupled to the horizontal linear guide and translates across the horizontal support surface along one side of the bed. The plurality of rungs include swing sections mounted on hinges which hang vertically when the translatable vertical upright is positioned adjacent to the fixed vertical upright. When the translatable upright is positioned away from the fixed upright, the swing sections are supported in a horizontal position.
Two principal embodiments of the invention are taught. In a first embodiment, the swing sections of the rungs are anchored with respect to the fixed upright, and are interconnected by a tether which is attached to the free ends of the sections and, at one end of the tether, to the translatable upright. Lifting upwardly on the top one of swinging sections lifts all of the sections and pulls the translatable upright away from its stowed position. In the second described embodiment, the swing sections of the rungs are anchored on the translatable upright. Pulling the translating upright outwardly from its stowed position causes the swing sections of the rungs to ride upwardly on openings in the fixed upright, through which the swing sections are positioned, until they are raised, supported in a horizontal position on the fixed upright.
Additional effects, features and advantages will be apparent in the written description that follows.